Percy Jackson and the Elements Thief
by hadesgirl015
Summary: Sequel to "The Princess of Thieves," (but also a cross-over). It has been a year since Percy, Nico and Natalie's mission. But after babysitting Percy's mortal half-sister, the three of them get tossed into a world full of...ponies? The Elements of Harmony have been stolen and Princess Celestia needs them along with some of the ponies to retrieve them. But will they be able to?
1. Chapter 1

**Disclaimer: I don't own Percy Jackson or My Little Pony, I only own Natalie and Cassidy. **

Chapter 1 Percy: Babysitting

It was about a year since my mission with Nico di' Angelo and Natalie Cox. We had to go and get all the gods symbols of power back from Eris. Along the way, Natalie, a daughter of Hermes, and Nico started going out, quite suddenly I might add. I think it started once Nico was turned back to being human, after Eris turned him into a duck.

Anyway, I was sitting in my cabin alone, because Tyson doesn't come around much any more, when my salt water fountain I use for Iris messages started glowing.

"Please insert one golden drachma for the call." the voice, I now knew belonged to Iris said. I knew it had to be my mom, she is the only one who Iris messages me, and makes me pay for it. I sighed and pulled out a drachma and the rainbow flickered to show my mom and step-dad Paul standing in the kitchen of the apartment.

"Hey, Percy, how are you?" my mom asked.

"I'm fine mom. Do you need something?" I said. I didn't mean to sound rude but that is the only reason mom contacts me while I am at Camp Half-Blood.

"Oh honey can you come and baby-sit your sister?" Mom asked.

"You and Paul going somewhere?" I asked. I knew I was probably a last resort, a free babysitter for my half-sister. She is three now. They would not ask me to baby-sit unless they couldn't get any one else, because they don't trust me with her much. But hey I'm ADHD.

"Well not together. Paul is speaking at a collage seminar, and I have a meeting talking about a book signing." Mom said.

I sighed, I can't get of this. "Okay mom, I'll get Blackjack to take me over there." I said.

"Thank you sweetie." Mom said. Besides being 20 I didn't mind mom calling me that.

I swiped my hand through the rainbow, and image faded. I left my cabin and found Chiron teaching archery.

"Chiron, my mom needs me to baby-sit." I said.

"I understand Percy." Chiron said.

I continued towards the stables.

"Blackjack come on." I said. Blackjack was a pure black pegasus, and he adored me. Ever since I rescued him from Luke back after my mission in the Sea of Monsters, he has insisted in helping me whenever I need it. And since Poseidon, my father, created horses, and the first Pegasus is also my brother, it is the only way I can fly without making Zeus upset, and trying to blast me out of the sky.

"_Yo boss, need to go somewhere?_" Blackjack said in my mind. It's a son of Poseidon thing.

"Yeah I need to get to my mom apartment, in Manhattan." I said. "And don't call me boss."

"_Whatever you say boss._" Blackjack said.

I sighed and led him out. When I was mounting Natalie and Nico came over.

"Hey, Percy, where are you going?" Nico asked.

"Babysitting." I said.

"Who?" Natalie asked.

"My half-sister. My mom's and step-dad's kid." I said.

"Awww," Natalie said.

"Will you guys come with me, it is going to be so boring watching her?" I asked.

"How are we going to get there?" Nico asked.

"Well, Natalie can fly with me, and I will contact you Nico when we get there, and you shadow travel there." I said.

"Okay." Nico said.

"I get to fly on a pegasus?" Natalie asked.

"_Whoa, boss, you sure about this?_" Blackjack asked.

"Blackjack, be nice." I said. I handed my arm to help Natalie up.

Blackjack tried to protest, but when I promised him donuts and sugar cubes, he stopped. Blackjack got us there in ten minutes flat. I had him drop us off at the street corner. Nobody lifted an eyebrow, but hey it is Manhattan, no matter what they saw it probably wasn't the weirdest thing they ever saw.

"Go head back to camp, Blackjack, you will get your donuts and sugar when I get back." I said.

"_Sure thing boss._" Blackjack said then he flew off.

"So is your apartment near here?" Natalie asked.

"Just down the street, about half a block." I said.

We headed down the street, when we came to my apartment building I went up the stairs to my floor. When we came to the door of my apartment I knocked. Paul answered the door.

"Hey, Percy. Who is this?" Paul asked noting Natalie.

"Natalie Cox, I'm just a friend of his." Natalie said.

"A friend, from camp?" Paul asked.

"Yeah." I said.

Natalie stared at me in shock. "He knows?"

"Yeah, so does my mom." I said.

"Who is her parent?" Paul asked.

"Hermes." Natalie asked.

Paul stared at her skeptically, as if wondering if she would steal anything.

"I swear on the Styx that I won't steal anything." Natalie promised Paul.

"Okay, come in I guess." Paul said.

Paul led us into the living room where Cassidy, my three year old half-sister was sitting on the floor watching T.V.

"Well Percy, you know, try not to explode the apartment, in any way shape or form. But protect you sister. Hopefully no monsters come. I have to go now." Paul said then he left.

Cassidy looked at me, with slight confusion. I understood why, during summer she never sees me, and during the rest of the year I am usually busy.

"Hey Cassidy, it's me Percy you remember right?" I asked.

Cassidy broke into a grin. She had my mom's brown hair and blue eyes. **(A/N Sally's eyes change in the light, but are mostly blue.) **But she had Paul's nose, and strangely she had my smile.

"Percy!" Cassidy said, she got up from her spot on the floor and came over to give me a hug, which was a bit odd because she barely came up to my waist. "Watch ponies!" she dragged me to the couch basically ordering me to sit down with her.

She went back over to Natalie.

"Who are you?" Cassidy asked.

"I'm Natalie." Natalie said.

"Are you special like Percy?" Cassidy asked.

"Yeah." Natalie said. "I'm going to tell Nico to come over now. Should I do it in the bathroom?"

"Kitchen is fine." I said. Natalie went to the kitchen. I was happy that she was the one Iris messaging Nico, because she gets them for free, because her dad is the messenger god.

Cassidy came over and sat next to me on the couch, I had to help her up. I turned to see what we were watching. On the screen was horses, talking, colorful horses. I mean some of the horses were blue, others pink. Their manes were also odd colors. Some were pegasi, others were unicorns, then there were regular horses, or as regular as they can be on a cartoon. Most of the horses had tattoos on their flanks, of different things, like apples, butterflies, or even lightning bolt that looked like a rainbow.

"Ponies!" Cassidy said pointing to the screen.

"Yeah I can see that." I said.

Natalie came back into the room. "Nico will be here soon." Natalie said.

"Nico?" Cassidy asked.

"A friend." I told her.

Natalie turned to see what we were watching. "My Little Pony: Friendship is Magic?"

"I guess." Percy said.

"AHHHHH!" Cassidy screamed, pointing to the corner.

"Whoa, don't call the cops, it is just me." Nico said.

Nico had shadow traveled into the corner.

"Nico, there is something called a door." Percy said.

"But doors are no fun." Nico complained.

"Nico, don't complain, you are seventeen. Especially in front of the two-year-old." Natalie said

"I three!" Cassidy said.

"Oh sorry." Natalie said.

"What are we watching?" Nico said.

"Ponies!" Cassidy said happily.

"My Little Pony." Natalie said.

"How do you know so much about this?" I asked.

"Well Conner and I wanted a way to prank the Ares cabin. So he asked the Hebe cabin for help." Natalie asked.

"Hebe? Isn't she like the goddess of childhood?" Nico asked.

"Preciously. We asked for information on children's shows. They gave us all three seasons of this. We watched them all." Natalie said.

"Then?" Nico asked.

"We painted Ponyville on one side of the cabin, on the other sides we painted the main ponies." Natalie said. She broke into her grin.

"That is why Chiron grounded you?" Nico asked.

"Yeah." Natalie said. "The show is actually pretty good, Travis refuses to give back the DVD. He is such a brony."

I gave her a confused look.

"A brony is an older boy or man who like My Little Pony." Natalie said.

Cassidy behaved well since they had My Little Pony on Netflex. They watch four straight hours of it, until my mom came back.

"Mommy!" Cassidy said and ran into mom's open arms.

"Hey, Cassidy, did you have fun with you big brother?" Mom asked.

"Yes I had so much fun with Percy, Natalie and Nico! We watched Ponies!" Cassidy said.

"Did you know?" Mom asked. "Percy you had friends over?"

"Mom, no way was I going to be able to watch a three year-old for four hours without help." I defended.

"Okay so it's Nico but who is this?" Mom asked.

"Natalie Cox, daughter of Hermes." Natalie said. "And I did not take anything."

"Okay. Well you three best head back to camp." Mom said.

"Bye Mom." I said. "Nico can you get us back?"

"Yeah." Nico said.

"Oh, we need to stop by the donut shop first, I promised Blackjack donuts and sugar cubes so he would take Natalie." Percy said.

"Fine." Nico said.

We linked hands and disappeared into shadows.


	2. Chapter 2

**I don't own Percy Jackson or My Little Pony. **

Chapter 2 Natalie: What Happened

I still can't believe we watched four straight hours of My Little Pony, Travis would be so jealous. But sadly we had to return to camp. Cassidy was so cute too. She was at that age where little kids get bossy in that cute way like, "watch ponies." And you know you can't say no to them less you are in so much trouble I doubt the gods can help you.

Percy, Nico and I returned from Manhattan back to Camp just in time for the campfire. After the campfire, I got questioned by my nosy brother, Travis and Conner Stoll. They always get up in my face, maybe because they are worried about me, or because I still have over $1,500 from my time in the Cash Cab after my quest. Chris pretty much stayed out of my business, but he has a girlfriend after all. And Josh, he was new to camp, only 10, and my newest brother, he couldn't order me around.

"Where were you?" Conner asked.

"I was with Nico…" I started.

"Alone!" Travis said, so loud I was wondering how long it would take the wood nymphs to come and yell at us to be quite.

"…and Percy." I continued.

"Where?" Conner asked.

"Percy's mom's apartment." I said.

"Why?" Travis asked.

"Watching his mortal half-sister." I said.

"And?" Conner asked.

"We watched four hours of My Little Pony." I said.

Travis gasped. "No fair, we have to go to classes and you just go and watch My Little Pony?"

"Percy wanted help babysitting, she is three years old." I said.

"This is not over young lady!" Conner said.

Young lady? I'm seventeen you are what, eighteen? One year older, get over it.

"Lights out." Travis said.

I went behind my curtain, that separated a portion of the cabin, because I was the only girl in the cabin with four boys.

After I fell asleep I had a dream. I hate dreams, dreams for demigods usually mean a few things, A.) Something bad is happening. B.) Something bad will happen in the near future. C.) You are seeing something important or sometimes scary from the past. D.) You are seeing something going down right as the dream is happening. Or my personal favorite note the sarcasm, E.) Some baddie is trying to get you to join them.

I was on the beach I knew too well, the Gulf of Mexico. Where in multiple dreams Chaos tried to recruit me. As I stood there I heard the familiar voice of Chaos.

"Did you steal them?" Chaos said.

"Yes I did. And there is nothing those ponies can do about it." The voice sounded familiar, it was feminine. And ponies, what the Hades?

"Soon you can bring your army here and we shall rule both worlds." Chaos said.

"What about the heroes that stopped you last time?" the voice asked.

"There is nothing they can do, they can't even get there." Chaos said.

I jolted awake. I was about to go tell Chiron when my curtain transformed into a portal. I tried my best not to be pulled in but it eventually did, and I blacked out.

When I woke up I could definitely tell I wasn't at Camp Half-Blood anymore. I was in a grassy field I could see some apple trees in the distance. But something seemed odd. The place seemed familiar and yet I knew I had never been here before.

I look over to my right and I see a blue-green unicorn. Wait a blue-green unicorn. It had a black mane and it was passed out to. I saw on its flank a tattoo of an ocean wave overlaid with a sword. To my left I was a light grey pony, it also had a black mane, but its tattoo on its flank was bones. Creepy. I looked down on myself and realized, I wasn't myself. I stood up uneasily then I realized I had four hooves. When I stumbled I caught myself before I hit the ground by…flying? I had wings. I flew low over to a pond and looked in at it. In my reflection was a white pegasus with an auburn mane and blue eyes.

I was a pegasus. I looked on my flank and saw tattooed on it was a caduceus. I had been transported into My Little Pony. I flew still uneasily over to the other too. I quickly decided they were boys, and something felt odd about them. I looked over to the pony and nudged it with my hoof. Its eyes shot open revealing deep brown eyes I would know anywhere, the horse was Nico!

"Nico it's me, Natalie." I said.

"You're a pegasus." Nico said. Yeah Nico was not a morning person.

"Nico you're a horse." I said.

"What the Hades!" Nico said and shot to his feet…hooves I guess. "Are we in My Little Pony?"

"It looks like it." I said. I walked over to the unicorn pretty sure who it was already. I poked him with my hoof and he shot up immediately. His sea-green eyes were a give a way.

"Percy, don't freak out. We have been somehow put into My Little Pony. It's me Natalie, and that, is Nico." I said pointing with my hoof.

"Oh Styx." Percy muttered.

"Well at least you two are cool, I'm a pony for gods' sake. You two at least get flying and magic." Nico complained.

"Nico what did I say about complaining?" I asked.

"You said not to do it in front of three-year-olds." Nico pointed out.

"Hey, you think I'm happy, I am twenty years old, and a freaking unicorn." Percy said.

"And we are seventeen, calm down Percy." I said.

"Percy is this you're doing?" Nico asked.

"How could it be my doing?" Percy asked.

"Your dad created horses, and your brother is Pegasus. Tell me what in the world is going on!" Nico said.

"Nico calm down, blaming Percy is not going to solve the problem." I said.

"Then what is?" Nico asked

I was about to answer when I heard humming, I looked over to where it was coming from. I saw a familiar purple unicorn with a dark purple mane, which had a pink streak.

"Oh, hello, are you new? I haven't seen you around." She said.

"Yeah, we just got here." I said.

"Well my name is Twilight Sparkle, and who might you be?" Twilight asked.

"Percy." Percy said.

"Nico." Nico said.

"I'm Natalie." I said.

"Hmm, I never heard of anything like those names before." Twilight said. "Where are you from?"

Dang she was more nosy then a new child of Athena.

"Manhattan." Percy said.

Twilight paused for a bit, "Manehatten?"

"No listen, can we go someplace where we can talk privately? Something strange sort of happened." I said.

"Um, sure follow me to my house." Twilight said. She led us down the dirt path.

"Oh gods," I thought to myself. "How are we going to explain this?"

When we got to Twilight's tree/library/house, she closed the door.

"So what is wrong?" Twilight asked.

"Okay, listen, this may sound crazy, but we are from a different world." I said.

"What do you mean?" Twilight asked.

"We aren't ponies, we are humans." Percy said.

"Huh?" Twilight asked.

"We have no idea what. We went to bed last night, and woke up here." I said.

"Okay, this is weird." Twilight said.

"We know." Nico said.

"Maybe I could contact Princess Celestia, she might have an idea." Twilight said. "Spike, come in here please."

Spike, Twilight's friendly baby purple dragon came in.

"Hey, Twilight what is it?" Spike asked coming in. "Who are these guys?"

"They are new, but apparently they aren't from here." Twilight said.

"Where are they from?" Spike asked.

"We are from a different world." I said.

"Different world?" Spike asked.

"Spike take a note to Princess Celestia. 'Dear Princess Celestia, three ponies have showed up, they have claimed to come from a completely different world. They have no idea how they have arrived in Equestria. We are in desperate need of your advice. Your dearest student Twilight Sparkle.' Got that Spike?" Twilight said.

"Yeah. Send it now?" Spike asked.

"Right now." Twilight said.

Spike blew flames on the note to send it to Princess Celestia.

"So what are your guys' talents?" Twilight asked.


	3. Aurthors Note

**I regret to inform you that I will be discontinuing this story until futher notice. I am sorry for you who have really enjoyed this story, but honestly I don't know what I was thinking. But I plan on writing a gods and demigods read the seres, series. Read those or some of my other works.**

**With deepest regrets,  
Hadesgirl015**


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